Leonardo da Vinci, the great genius of the Renaissance, developed and
practiced a unique synthesis of art, science, and technology, which is
not only extremely interesting in its conception but also very relevant
to our time.

As we recognize that our sciences and technologies have become
increasingly narrow in their focus, unable to understand our
multi-faceted problems from an interdisciplinary perspective, we
urgently need a science and technology that honor and respect the unity
of all life, recognize the fundamental interdependence of all natural
phenomena, and reconnect us with the living Earth. What we need today is
exactly the kind of synthesis Leonardo outlined 500 years ago.

A science of living forms

At the core of Leonardo's synthesis lies his life-long quest for
understanding the nature of the living forms of nature. He asserts
repeatedly that painting involves the study of natural forms, of
qualities, and he emphasizes the intimate connection between the
artistic representation of those forms and the intellectual
understanding of their intrinsic nature and underlying principles. In
order to paint nature's living forms, Leonardo felt that he needed a
scientific understanding of their intrinsic nature and underlying
principles, and in order to analyze the forms of nature, he needed the
artistic ability to draw them. His science cannot be understood without
his art, nor his art without the science.

The quest for the secret of life

I have been fascinated by the genius of Leonardo Lea Vinci and have
spent the last ten years studying his scientific writings in facsimile
editions of his famous notebooks. In my new book, I present an in-depth
discussion of the main branches of Leonardo's scientific work — his
fluid dynamics, geology, botany, mechanics, science of flight, and
anatomy. Most of his astonishing discoveries and achievements in these
fields are virtually unknown to the general public.

What emerged from my explorations of all the branches of Leonardo's
science was the realization that, at the most fundamental level,
Leonardo always sought to understand the nature of life. My main thesis
is that the science of Leonardo da Vinci is a science of living forms,
radically different from the mechanistic science of Galileo, Descartes,
and Newton that emerged 200 years later.

This has often escaped earlier commentators, because until recently the
nature of life was defined by biologists only in terms of cells and
molecules, to which Leonardo, living two centuries before the invention
of the microscope, had no access. But today, a new systemic
understanding of life is emerging at the forefront of science — an
understanding in terms of metabolic processes and their patterns of
organization; and those are precisely the phenomena which Leonardo
explored throughout his life, both in the macrocosm of the Earth and in
the microcosm of the human body.

In the macrocosm, the main themes of Leonardo's science were the
movements of water, the geological forms and transformations of the
Earth, and the botanical diversity and growth patterns of plants. In the
microcosm, his main focus was on the human body — its beauty and
proportions, the mechanics of its movements, and the understanding of
the nature and origin of life. Let me give you a very brief summary of
his achievements in these diverse scientific fields.

The movements of water

Leonardo was fascinated by water in all its manifestations. He
recognized its fundamental role as life's medium and vital fluid, as the
matrix of all organic forms: "It is the expansion and humor of all
living bodies," he wrote. "Without it nothing retains its original
form." This view of the essential role of water in biological life is
fully borne out by modern science. Today we know not only that all
living organisms need water for transporting nutrients to their tissues,
but also that life on Earth began in water, and that for billions of
years, all the cells that compose living organisms have continued to
flourish and evolve in watery environments. So, Leonardo was completely
correct in viewing water as the carrier and matrix of life.

Throughout his life, Leonardo studied its movements and flows, drew and
analyzed its waves and vortices. He experimented not only with water but
also investigated the flows of blood, wine, oil, and even those of sand
and grains. He was the first to formulate the basic principles of flow,
and he recognized that they are the same for all fluids. These
observations establish Leonardo da Vinci as a pioneer in the discipline
known today as fluid dynamics.

Leonardo's manuscripts are full of exquisite drawings of spiraling
vortices and other patterns of turbulence in water and air, which until
now have never been analyzed in detail, because the physics of turbulent
flows is notoriously difficult. In this book, I present an in-depth
analysis of Leonardo's drawings of turbulent flows, based on extensive
discussions with Ugo Piomelli, professor of fluid dynamics at Queen's
University in Canada, who very generously helped me to analyze all of
Leonardo's drawings and descriptions of turbulent flows.

The living Earth

Leonardo saw water as the chief agent in the formation of the Earth's
surface. This awareness of the continual interaction of water and rocks
impelled him to undertake extensive studies in geology, which informed
the fantastic rock formations that appear so often in the shadowy
backgrounds of his paintings. His geological observations are stunning
not only by their great accuracy, but also because they led him to
formulate general principles that were rediscovered only centuries later
and are still used by geologists today.

Leonardo was the first to postulate that the forms of the Earth are the
result of slow processes taking place over long epochs of what we now
call geological time.

With this view, Leonardo was centuries ahead of his time. Geologists
became aware of the great duration of geological time only in the early
19th century with the work of Charles Lyell, who is often considered the
father of modern geology.

Leonardo was also the first to identify folds of rock strata. His
descriptions of how rocks are formed over enormously long periods of
time in layers of sedimentation and are subsequently shaped and folded
by powerful geological forces come close to an evolutionary perspective.
He arrived at this perspective 300 years before Charles Darwin, who
also found inspiration for evolutionary thought in geology.

The growth of plants

Leonardo's notebookd contain numerous drawings of trees and flowering
plants, many of them masterpieces of detailed botanical imagery. These
drawings were at first made as studies for paintings, but soon turned
into genuine scientific inquiries about the patterns of metabolism and
growth that underlie all botanical forms. Leonardo paid special
attention to the nourishment of plants by sunlight and water, and to the
transport of the sap through the plants' tissues.

He correctly distinguished between the dead outer layer of a tree's bark
and the living inner bark, known to botanists as the phloem, which he
called very aptly "the shirt that lies between the bark and the wood."
He was also the first to recognize that the age of a tree corresponds to
the number of rings in the cross-section of its trunk, and — even more
remarkably — that the width of a growth ring is an indication of the
climate during the corresponding year. As in so many other fields,
Leonardo carried his botanical thinking far beyond that of his peers,
establishing himself as the first great theorist in botany.

The human body in motion

Whenever Leonardo explored the forms of nature in the macrocosm, he also
looked for similarities of patterns and processes in the human body. In
order to study the body's organic forms, he dissected numerous corpses
of humans and animals, and examined their bones, joints, muscles, and
nerves, drawing them with an accuracy and clarity never seen before.
Leonardo demonstrated in countless elaborate and stunning drawings how
nerves, muscles, tendons and bones work together to move the body.

Unlike Descartes, Leonardo never thought of the body as a machine, even
though he was a brilliant engineer who designed countless machines and
mechanical devices. He clearly recognized that the anatomies of animals
and humans involve mechanical functions. "Nature cannot give movement to
animals without mechanical instruments," he explained, but that did not
imply for him that living organisms were machines. It only implied
that, in order to understand the movements of the animal body, he needed
to explore the principles of mechanics. Indeed, he saw this as the most
"noble" role of this branch of science.

Elements of mechanics

To understand in detail how nature's "mechanical instruments" work
together to move the body, Leonardo immersed himself in prolonged
studies of problems involving weights, forces, and movements — the
branches of mechanics known today as statics, dynamics, and kinematics.
While he studied the elementary principles of mechanics in relation to
the movements of the human body, he also applied them to the design of
numerous new machines, and as his fascination with the science of
mechanics grew, he explored ever more complex topics, anticipating
abstract principles that were centuries ahead of his time.

These include his understanding of the relativity of motion, his
discovery of the principle now known as Newton's third law of motion,
his intuitive grasp of the conservation of energy, and — perhaps most
remarkably — his anticipation of the law of energy dissipation, the
second law of thermodynamics. Although there are many books on
Leonardo's mechanical engineering, there is as yet none on his
theoretical mechanics. In the longest chapter of this book, I provide an
in-depth analysis of this important branch of Leonardo's science.

The science of flight

From the texts that accompany Leonardo's anatomical drawings we know
that he considered the human body as an animal body, as biologists do
today; and thus it is not surprising that he compared human movements
with the movements of various animals. What fascinated him more than any
other animal movement was the flight of birds. It was the inspiration
for one of the great passions in his life — the dream of flying.

The dream of flying like a bird is as old as humanity itself. But nobody
pursued it with more intensity, perseverance, and commitment to
meticulous research than Leonardo da Vinci. His science of flight
involved numerous disciplines — from aerodynamics to human anatomy, the
anatomy of birds, and mechanical engineering.

In my chapter on Leonardo's science of flight, I analyze his drawings
and writings on this subject in some detail, and I come to the
conclusion that he had a clear understanding of the origin of
aerodynamic lift, that he fully understood the essential features of
both soaring and flapping flight, and that he was the first to recognize
the principle of the wind tunnel — that a body moving through
stationary air is equivalent to air flowing over a stationary body. This
establishes Leonardo da Vinci as one of the great pioneers of
aerodynamics.

In his numerous designs of flying machines, Leonardo attempted to
imitate the complex flapping and gliding movements of birds. Many of
these designs were based on sound aerodynamic principles, and it was
only the weight of the materials available in the Renaissance that
prevented him from building viable models.

The mystery of life

As I have mentioned, the grand unifying theme of Leonardo's explorations
of the macro- and microcosm was his persistent quest to understand the
nature of life. This quest reached its climax in the anatomical studies
he carried out in Milan and Rome when he was over sixty, especially in
his investigations of the heart — the bodily organ that has served as
the foremost symbol of human existence and emotional life throughout the
ages. He not only understood and pictured the heart in ways no one had
before him; he also observed subtleties in its actions that would elude
medical researchers for centuries.

During the last decade of his life, Leonardo became intensely interested
in another aspect of the mystery of life — its origin in the processes
of reproduction and embryonic development. In his embryological studies,
he described the life processes of the fetus in the womb, including its
nourishment through the umbilical cord, in astonishing detail.
Leonardo's embryological drawings are graceful and touching revelations
of the mysteries surrounding the origins of life.

Leonardo knew very well that, ultimately, the nature and origin of life
would remain a mystery, no matter how brilliant his scientific mind.
"Nature is full of infinite causes that have never occurred in
experience," he declared in his late forties, and as he got older, his
sense of mystery deepened. Nearly all the figures in his last paintings
have that smile that expresses the ineffable, often combined with a
pointing finger. "Mystery to Leonardo," wrote the famous art historian
Kenneth Clark, "was a shadow, a smile, and a finger pointing into
darkness."